This invention relates to a method and apparatus for fastening together the frame elements of a picture frame or the like, and to a frame formed by the method and apparatus.
In the production of frames of the type used to mount picture or mirrors and similar objects, and in the production of panel doors for kitchen cabinets and the like and the frames for the door openings, the frame elements usually are formed with end surfaces oriented at 45.degree. angles with respect to the longitudinal axis of the frame elements with the grain of the wood extending along the length of each frame element and the angled end surfaces of each frame elements are matched together with a similar angled end surface of an adjacent frame element to form a 90.degree. mitered joint, and the frame elements are connected together by a fastener.
One process used for fastening mitered joints is to insert at least one nail into the outer edge surface of one frame element through that frame element, through the mitered joint, and into the adjacent frame element. As the fastener is driven through the mitered joint, it tends to compress or draw together the mitered joint. A second fastener can then be driven from the edge surface of the adjacent frame element through the mitered joint, and this usually forms a firm connection between the frame elements. Some disadvantages of this type connection procedure are that the head portions of the fasteners are visible at the edge of the frame when the frame is hung on a wall, or if the fasteners are counter sunk into the frame elements the holes or the putty covering the holes are visible, a multiple number of fasteners are required for each joint to form a stable frame, there is a hazzard that the fasteners will hit each other as they are driven into the frame, and if the frame is held in a jig and fasteners are driven simultaneously through both of the frame elements at the corner of the frame, two fastener tools are required for the process.
Another process for joining frame elements together in a mitered joint is to place the angled end surfaces of the frame elements together to form the mitered joint and then to insert a staple or similar fastener into the back surfaces of the frame elements at a right angle with respect to the surfaces of the frame elements so that the fastener straddles and therefore connects together the frame elements. Since the movement of the fastener into the surfaces of the frame elements usually does not tend to draw the frame elements together, the firmness of the connection between the frame elements depends upon the operator's technique, and if the operator is not diligent in pressing the frame elements together during the fastening procedure, a loose joint is formed.
Another process for joining frame elements together in a mitered joint is to form a kerf in each frame element adjacent the mitered joint on the unexposed surfaces of the joint and extending outwardly from the inside surfaces of the joint and then inserting a clamp into the kerfs. A disadvantage of this process is that it requires additional labor and time, and therefore is expensive.
None of the frame fastening processes known to the inventors provide the advantages of drawing the mitered joint together by the movement of the fastener into the material, using a single fastener, inserting the fastener into the rear or unexposed surface of the mitered joint, and expediently and inexpensively forming and fastening the mitered joint.